Both viscosities are withen spec. Check your owners manual for which to use depending on temperatures where you live. Should you switch your oil because of the age of the car? No. You can go to a high mileage oil if you like.

yeah, don't change viscosity to anything not recommended in Owner's Guide. most Toyota (covered by this section of forums) are recommended to run on 5w-30 in colder climates (or more variable) while 10w-30 can be used instead in warmer climates (always above -18C/0F).

at least this is how I read the guide (pic borrowed from another thread, based on gen4 camry engines 5s-fe and 1mz-fe):

as mentioned above, you can switch type of oil to High Mileage if you feel it would help or if you have some seeping seals (though it's rather recommended to fix them mechanically and not chemically).

you can also switch engine oil type from mineral (dino/classic) to synthetic of same viscosity if you like, it will benefit you with longer oil change intervals (synthetics wear down slower than dino oils).

'02 Solara SLE V6 1MZ-FE/A541E@ 149k"We are what we repeatedly do. Excellence, then, is not an act, but a habit." - Aristotleitems For Sale

hmm... didn't realize 10w-30 is better for HM engines.
maybe I will start running my noisy 5s-fe on 10w-30 since Spring (I have 5w-30 M1 FS for Winter) and see what happens.

Well the 10w30 is a higher viscosity (thicker) than the 5w30

the 5w30 is good for cold starts though because it lubricates the motor faster

5W-30 or the 10W-30 is strictly a matter of choice. With the small differences in kinematic viscosity you would be hard-pressed to detect these differences on initial engine start-up without specialized engine test equipment.

at operating temperature both of these oils work pretty much the same though. I wouldn't switch to 10w30 for the winter though because 5w30 is designed to pressurize better in cold conditions. 10w30 is too thick to build the right amount of pressure and takes longer to heat up than 5w30 ( poor circulation )

Do what the manual tells you to dooooo. The manual is all knowingggggg.

my manual says to use 5w30 or 10w30. I run 10w30 during the summer time and 5w30 in the winter.

My oil cap on my 95 says 10w30 and my 92 and 93 just say OIL FILL or something like that

If you are running 10w30 during the winter something to look into would be an engine block heater. It hooks onto your oilpan magnetically and heats your oil pan so when you start your vehicle, your oil is already thinned out and has good circulation right off the bat. Just dont forget to unplug it!

Just use a full synthetic and don't worry about the oil weigh. 0w20, 5w20, 0w30, 5w30, 10w30, 0w40, 5w40, 10w40...... all will work well and have worked great for me. I've even run 15w50 during our northeast cold winter.

5w30 and 10w30 are the same viscosity range at normal running temp. 30 falls between 9.3-12.5cst at 100c.

5w is tested at -30c(cranking) and -35c(pumping)
10w is tested at -25c and -30c...
25w is test at -10c and -15c
How cold does it get where you live?

If you don't live in the Santa household, quit worrying.

Because the 1997-2001 engines are sludge monsters(caused by cooking oil), I recommend that you use a full synthetic, check the oil every 500 miles, top off as needed, and keep the oil change interval reasonable. As long as the oil is full synthetic, I could care less what your oil weight is or what the owners manual recommends.

From Mobil1's website:
5w30 is 11.1cst
10w30 is 10.7cst
Higher number is thicker so which is???

And even more extreme, Castrol syntec:
0w30 is 12.1cst
10w30 is 10.1cst
Again, which is thicker?

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